The overall objective of this research is to develop new microanalytical approaches to study the neurochemistry of Drosophila melanogaster, the fruit fly. Drosophila is arguably one of the most studied organisms in biology offering many advantages as a model system. However, there is a difficulty with a need for low-volume and sensitive analytical methods to examine the chemical changes associated with genetic and behavioral aspects of the fly. The fly nervous system contains approximately 200,000 cells and occupies only about 8 nL. We propose to further develop and apply small sample handling and capillary electrophoresis methods we have recently reported for studies with the fly. These methods have produced some of the richest electropherograms or chromatograms for electrical detection of a biological sample reported to date and there are many compounds eluted that we have not yet identified. In addition, we propose to use one Pi's background in in vivo voltammetry to develop protocols for in vivo voltammetry in the fly. This will present the smallest in vivo approach in an intact organism and is an exciting analytical challenge. Current and newly developed methods will be brought to bear on the chemical mechanisms that underlie chronic alcohol tolerance and the analysis of single fly outliers. The aims of the proposal are to 1) enhance sampling methodologies for analytical separations of fly homogenates, single heads, and sections of nervous tissue, 2) develop in vivo electrochemical methods for the chemical analysis of dynamics in distinct fly brain structures, and 3) apply the newly developed techniques to identify neurochemicals associated with chronic tolerance to alcohol.